Analysis of Capacitor Voltage Imbalance in Hybrid Converters and
Inherently Balanced Operation Using Symmetric Architecture
Abstract
This paper investigates the origin of the flying capacitor voltage
imbalance in hybrid converters. By observation and logical deduction, an
intuitive voltage-charge relationship is established which can give a
general explanation of the flying capacitor voltage balance in hybrid
converters. This relationship can establish a relatively simple and
intuitive method to identify the difference of balance performance in
hybrid converters for Vout<(Vin /N) cases.
Converter with even number of inductor charging intervals, are shown to
be susceptible to flying capacitor voltage imbalance, while flying
capacitors in hybrid converters with inductors having odd charging
intervals have inherently balanced operations. As a direct result of the
analysis, a new symmetric operation of FCML converters is introduced to
achieve an inherent balance of flying capacitor voltages. Hardware
implementations and experiments have been carried out for verifications
of the analytical analysis and the new symmetric operation.